Sheldon and Leonard hire Professor Proton (guest star BOB NEWHART), the host of their favorite childhood TV show, to perform. Also, Howard and Bernadette run into trouble babysitting Raj’s dog.
Patrick Jane and the CBI team are pulled deep inside the world of horse racing after a jockey is found murdered and suspects abound.
Kidd and Severide’s honeymoon is interrupted by a dangerous person from their past. Kidd’s former academy classmate joins Firehouse 51. Brett and Violet reflect on their relationships.
Det. Pryma’s case comes to an explosive end with Kidd and Carver’s lives in danger. Brett installs an infant Safe Surrender Box at 51. Violet is determined to take Emma down.
Severide struggles with the cost of helping Det. Pryma with the Martucci case. Gallo campaigns for Herrmann to represent 51 at the National Firefighter’s Association’s Winter Conference. A familiar face makes a shocking return.